FamilyTreeDNA is offering a free transfer of autosomal DNA test data from Ancestry.com and 23andMe.com, but with strings attached.
From Roberta Estes' DNAeXplained website:
"In order to attract more uploads, which will, of course, give us more
matches, Family Tree DNA is announcing free uploads from Ancestry and
23andMe, the v3 chip only, but with a string attached. The transferee can
do the actual transfer for free, but they will only see their top 20
matches, only an initial and a last name, and will not be able to communicate
with them unless they decide to pay $39 to join, or perhaps stated more
accurately, to active all of the features of a paid transfer. However, in
lieu of the $39 fee, you can also recruit 4 other people to upload their data,
whether or not they actually pay the fee or not."
Realize that you will be transferring just your DNA data and not your matches to FamilyTreeDNA. FamilyTreeDNA will compare this data to their database and this will be the results that you get. If you already have an autosomal DNA test with FamilyTreeDNA there will no advantage to transferring either Ancestry or 23andMe data to FamilyTree.
More information can be found on Blaine Bettinger's The Genetic Genealogist website.
Happy ancestor hunting.